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Wittig reagents are usually prepared from a phosphonium salt, which is in turn prepared by the quaternization of triphenylphosphine with an alkyl halide. Wittig reagents are usually derived from a primary alkyl halide. Quaternization of triphenylphosphine with secondary halides is typically inefficient.
It is the parent member of the phosphorus ylides, popularly known as Wittig reagents. It is a highly polar, highly basic species. It is a highly polar, highly basic species. Preparation and use
This reagent reacts with a ketone or aldehyde in a Wittig reaction to give an enol ether, which can be converted to the aldehyde by acid-induced hydrolysis. The initial report of the reaction demonstrated its use on the steroid tigogenone. It was later used in the Wender Taxol total synthesis and the Stork quinine total synthesis.
The Wittig reaction or Wittig olefination is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide called a Wittig reagent. Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. [1] [2] [3] Most often, the Wittig reaction is used to introduce a methylene group using ...
Wittig reagents are used in organic synthesis. They are derived from phosphonium salts. A strong base such as butyllithium or sodium amide is required for the deprotonation: [Ph 3 P + CH 2 R]X − + C 4 H 9 Li → Ph 3 P=CHR + LiX + C 4 H 10. One of the simplest ylides is methylenetriphenylphosphorane (Ph 3 P=CH 2). [6]
The methylation of triphenylphosphine is the first step in the preparation of the Wittig reagent. Illustrative phosphorus(V) compounds: the phosphonium ion P(CH 2 OH) 4 +, two resonance structures for the Wittig reagent Ph 3 PCH 2, and pentaphenylphosphorane, a rare pentaorganophophorus compound. The parent phosphorane (σ 5 λ 5) is PH 5 ...
It undergoes a Wittig reaction. [1] It is used in the Vitamin B12 total synthesis. Production
It is also the starting point for the preparation of several other reagents. For example, the related Wittig reagent (prepared by reaction with triphenylphosphine) is commonly used to prepare alpha,beta-unsaturated esters from carbonyl compounds such as benzaldehyde: [9] Ethyl bromoacetate as the starting point for a Wittig reaction sequence
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